Panel board cabinet



April 1954 N. J. SCHMELIG PANEL BOARD CABINET Filed March 29, 1952 F I62. 5 f /7 f f Patented Apr. 13, 1954 PANEL BOARD CABINET Nicholas J. Schmelig, St. Louis, Mo., assignor to Frank Adam Electric Company, St. Louis, Mo., a corporation of Missouri Application March 29, 1952, Serial No. 279,338

This invention relates-to cabinets for electric switch gear and the like, and more particularly to panelboard cabinets having detachable conductor-entry panels.

Panelboards and switchboards are commonly enclosed within a sheet metal cabinet having doors which may be locked to prevent unauthorized access to the switch gear, protective devices and other electrical apparatus therein contained. Because the cabinet usually has to be tailored, at the time of installation, to fit previously illstalled runs of conduit, cable or duct, it has become theaccepted practice in the industry to provide such cabinets with a panel which may be removed by the installing workman after the cabinet is properly oriented with reference to the fixed situation of the external conductors. In this way, the installing workman is enabled to accurately locate the proper position at which to cut conductor entry openings while the removable panel is in position on the cabinet; then remove the panel to a convenient work bench for cutting the appropriate openings. The cutting of the openings while the panel is in situ is universally discouraged for several reasons, among which may be mentioned the likelihood that chips of metalmay drop into the electrical apparatus and go undiscovered until the juice is turned on; whereupon'serious damage might re sult. Heretofore, such removable panels have been secured to the body of the cabinets by bolts and nuts, with the nuts on the interior. For security reasons, the heads of the bolts are preferably of a character which do admit of manipulation by screwdrivers or wrenches applied from the exterior. In order to comply with the standards laid down by the Underwriters Laboratory, a great multiplicity of such bolts and nuts is required, for example, a cabinet twelve inches deep and two feet wide is required to have between fifteen and twenty bolts securing a removable top about three sides thereof.

The fact that the securing bolts are so many, and the further fact that the. nuts thereon are so difficultly accessible and their manipulation (both in removal and replacement) hindered not only by their corner location, but also by the proximity of electrical apparatus already mounted in the cabinet, in many instances has induced, and always tempts, the installers to avoid the onerous task by cutting the conductor entry openings without removing the removable panel, This not onlydefeats the purpose of the removable panel, and renders useless the additional expense to which the panelboard manu 3 Claims. (Cl. 220-33) facture went in drilling the matching holes and threading up the bolts and nuts at the time of manufacture (better that the structure had been welded together in the first instance), but also may lead to serious consequences. While the onerous task imposed upon the installer would be mitigated if the manufacturer delivered the panelboard with the removable panel wholly unconnected, such is not feasible because the structure requires the added strength, provided by the removable panel, to withstand the rigors of handling and shipping.

It is accordingly an object of this invention to provide an improved panelboard cabinet having a conductor-entry panel that is more readily removed and replaced than those in prior types of such cabinets.

Another object of the invention is the provision of a panelboard cabinet that meets strength and construction requirements for such cabinets; and particularly the provision of a cabinet wherein the conductor-entry panel is secured at a sufilcient number of points about its "periphery, without requiring a separately manipulatable fastening at each such point.

, An additional object of this invention is the provision of a panelboard cabinet that is inexpensive to manufacture.

. In common with the prior practice, I provide a channel-shaped sheet metal body forming the back and sides of the cabinet. A swinging door may be hung on the front of the body and a suitable base afiixed at the bottom end. At the top of the channel-shaped body flanges are inturned from the back and sides. In accordance with my invention, however, a generally rectangular conductor-entry panel is seated on the aforesaid flanges, and the panel is secured thereto by lugs which are offset from the plane of the panel about the three of its edges which engage the flanges. These offset lugs engage beneath the three end flanges of the body, and are preferably struck from the panel, which may be of sheet metal. The lugs, which herein form fasteners, are preferably spaced apart distances corresponding to the spacing of fasteners in prior bolted types of cabinets. The panel is thereby slidably removable in a forward direction, and it is securable in its innermost position by but two bolts, located at the most accessible position therein.

Other features of the invention will be apparent from the following detail description taken in connection with the accompanying drawings, in which:

may be provided with a swinging. door hung at.

the front 7, and with a suitable base at one end 9. The sides are formedwith inwardly directed flanges H along the front, as indicated, and with inwardly directed flanges I3 at the top end. The back 3 has a similar end flange I5,

and these end flanges l3 and I5 form a support upon which aconductor-entry panel ll? is seated.

The conductor-entry panel H is a generally rectangular plateformed with a depending flange 1.9. at its forward edge, and with a plurality of lugs 21 offset downwardly and spaced about its three. other edges. Each lug, as best shown in Figures. 3 and 4, is struck. from the metal in such a. manner as tohave a depending leg 22 and an outwardly directed tongue 24. These legs 22 and tongues 26 have. a, snug engagement with the inner edges of the flanges l3 and i5 and grip against the underneath sides of these flanges respectively. In a. contemplated form of the invention, which has been approved by the Under writers Laboratory, each lug. may be threequarters. of an inch wide, and the spacing between the lugs may be two and three-quarters inches; In contrast to the bolt-and-nut fastened panels hereinbefore mentioned, however, no drilling of flanges. l3. and. [.5 is required. to provide for connection with the lugs 25, and the several lugs, irrespective of their sizev or spacing, may bev cut out and. offsetfrom the panel in. one operation of a, punch press. Moreover, all. of the lugs are engaged with. and disengaged from their respective cooperating flanges in one single motion.

Inasmuch as panelboard. cabinets are. generally manufactured from relatively heavy gauge sheet steel, for example; three-sixteenths. inch gauge, the lugs provide an: adequate fastening engagement. Near the front; the panel H and the side flanges t3 are suitably drilled to receive bolts 23, one bolt being located on each: side. It. will be seen that the conductor-entry panel may be readily detached from the body I of the cabinet by removing the bolts 23 and: withdrawing the panel in a forward direction. Suitable con.- ductor-entry apertures may then be cut, for example, as indicated by dotted lines at 25, according to whatever arrangement is desired. In thisv respect, the cabinet is ideally suited for installation where the. conduit and. wiring are already inplace. .This is because the installer may readily remove the conductor-entry panel and drill or cut conductor-entry apertures and afiix fittings as desired. The panel is then replaced by sliding it across the top end flanges l3, with the lugs 2| engaged beneath these flanges, to the innermost position, and is, then secured in position by means of the bolts 23 and nuts 21. A locking Washer may be used with the nuts 2'1 if desired.

The above construction, wherein the fasteners comprise bolts 23 at the forward edge and; offset entry lug members 2| spaced about the side and back edges, provides for a cabinet construction which is strong and rugged. It will be observed the snug engagement of the lugs at 22 with the inner edges of the end flanges I3 and i5 strengthens the body I against skewing, whereas the two bolts 23 at the. front of the body i prevent spreading of thezsides 5. In contrast to prior cabinets having detachable conductorpanels, however, the conductor-entry panel of this cabinet may be readily detached upon removal of only two "bolts instead of the numerous bolts which were heretofore employed.

From, the foregoing description, it is apparent that those skilled in the art will understand the structure, function, and mode of operation of the invention herein disclosed and appreciate the advantages thereof. While one embodiment has been disclosed in detail, it is to be understood that the invention. is not limited thereto, but the drawings and description thereof are to be understood as being merely illustrative. For examples, the panel may be placed under, instead of over the flanges l3 and I5 with the lugs 2| extending above the flanges rather than beneath the same asv described hereinbefore. It is realized that many modifications and variations will present themselves to those skilled in the art without. departing from the spirit of this. invention or the scope thereof as set forth in the appended claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is: r

1. A panelboard cabinet having a detachable conductor-entry panel, the cabinet comprising a sheet of metal bent to form a channel-shaped body with backand side panels, the margins at one end of the body being bent inwardly to form flanges along the back and side panels, a generally rectangular conductor-entry panel seated upon said flanges, said panel having a, plurality of spaced lugs struck from the panel and spaced about its side and back edgesto engage beneath said inwardly directed flanges on the body or"- the cabinet, said panel thereby being removable by withdrawal. in a forward. direction, and bolts securing the panel in its innermost position, said bolts being entered through the forward corners of the-panel andforward parts of the. side flanges to restrict spreading, of, the side panels,

2. A panelboard. cabinet. as set forth in claim 1 wherein the conductor-entry panel has. a depending flange at its forward edge and wherein the body portion of the cabinet has similar flanges extendingalong the front part of the side panels.

3. A panelboard cabinet. asset-forth; in claim 1 wherein said lugs are formed with depending legs which snugly'engagez the inner edges of the flanges at the top end of the body.

References Cited inthe file of this patent UNITED STATES PATENTS Number Name Date 601,568 Jacoby. Mar. 29, 1898 615,324 Toohey Dec. 6, 1898 1,099,986 Lutz et. a1. June 16, 1914 1,628,406 Hortonv May 10, 1927 2,558,599 Wiles June 26, 1951 g FOREIGN PATENTS Number Country Date 6,188 Netherlands Oct. 15 1921 

